Sodium-Sulfur Batteries vs. Solid Oxide Fuel Cells for Energy Storage

November 30, 2022

Are you in the market for energy storage? With the abundance of energy storage technology options available, choosing the best one can be challenging. Two of the most popular technologies in the market today are sodium-sulfur batteries and solid oxide fuel cells. In this article, we'll compare the two and explore the advantages and disadvantages of each.

Sodium-Sulfur Batteries

Sodium-sulfur batteries (NaS) are rechargeable batteries that use liquid sodium as the negative electrode and molten sulfur as the positive electrode. These batteries were first created in the 1960s but only gained popularity in recent years as a viable alternative for large-scale energy storage.

Advantages of Sodium-Sulfur Batteries

  • High energy density: Sodium-sulfur batteries have a specific energy of approximately 90 Wh/kg, making them among the highest energy density batteries available [1].
  • Long life cycle: Furthermore, these batteries have an expected life cycle of 10-15 years, making them a reliable option for long-term energy storage [2].
  • Cost-effective: Compared to other energy storage technologies, sodium-sulfur batteries are considered cost-effective.

Disadvantages of Sodium-Sulfur Batteries

  • High operating temperatures: Sodium-sulfur batteries operate at high temperatures of around 300-350°C, which can make them challenging to operate and potentially hazardous.
  • Large-scale storage only: Sodium-sulfur batteries are not suitable for small-scale applications and are usually only used for large-scale energy storage.

Solid Oxide Fuel Cells

Solid oxide fuel cells (SOFCs) are electrochemical devices that convert fuel and oxidants into electrical energy. These cells use a solid oxide electrolyte to separate the fuel and oxidants and produce electricity.

Advantages of Solid Oxide Fuel Cells

  • High efficiency: SOFCs have an electrical efficiency of 50-60%, which is considerably higher than other fuel cell technologies [3].
  • Flexibility: SOFCs can use a wide range of fuels, including natural gas and biogas, and are highly versatile.

Disadvantages of Solid Oxide Fuel Cells

  • Slow start-up time: SOFCs have a slow start-up time, taking several hours to achieve full power [4].
  • Expensive: SOFCs are currently one of the most expensive fuel cell technologies in the market.

Sodium-Sulfur Batteries vs. Solid Oxide Fuel Cells

Both sodium-sulfur batteries and solid oxide fuel cells are promising energy storage technologies. However, they have distinct differences that make them suitable for different applications.

  • Sodium-sulfur batteries are suitable for large-scale storage, whereas solid oxide fuel cells can be used for both small- and large-scale storage.
  • Sodium-sulfur batteries offer high energy density and long life, while SOFCs offer high efficiency and fuel flexibility.
  • Sodium-sulfur batteries operate at high temperatures, whereas SOFCs have a slow start-up time.

In summary, when choosing between sodium-sulfur batteries and SOFCs, consider the application's scale, required efficiency, and flexibility.


[1] "Energy Storage - Sodium Sulfur Batteries," Energy Storage Association, 2017. [Online]. Available:

[2] M. Lagadinos, N. Kyriakopoulos, and V. Karanikolas, "Review of sodium-sulfur batteries: Applications, materials and technologies," Journal of Energy Storage, vol. 18, pp. 392-407, 2018.

[3] Y. Ding, L. Luo, and Y. Tsai, "A review of solid oxide fuel cell technology," Renewable and Sustainable Energy Reviews, vol. 80, pp. 1143-1153, 2017.

[4] Y. Mishima et al., "Productivity of a Solid Oxide Fuel Cell Power Plant in Standby Mode," Journal of Fuel Cell Science and Technology, vol. 9, no. 6, 2012.

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